ABSTRACT The Host Response Core (Core C) will assist the research base and pilot project investigators by providing support to assess various endpoints and processes of inflammation, leukocyte activation, metabolism and the host response to bacteria relevant to cystic fibrosis (CF). This primary goal of the Host Response Core will be met by conducting a variety of routine and specialized procedures and assays and providing access to and training with sophisticated analytical and imaging equipment. To accomplish this goal the Host Response Core was incorporated into the existing, fully equipped Histology and Imaging Core, which is part of the Comparative Pathology Program in the Department of Comparative Medicine at the University of Washington. The primary services of Core C will be to conduct a variety of routine and specialized procedures and assays including histology, immunohistochemistry and imaging; provide access to automated immunohistochemistry and image analysis to assist CF investigators obtain quantitative histologic and immunohistochemical data; provide access to and expertise and training with sophisticated analytical and imaging equipment: provide access to comparative pathologists to assist and consult with basic research and preclinical studies; and promote increased interdisciplinary interactions to provide access to flow cytometry, metabolic profiling and training. The scientific focus of the Host Response Core is to obtain information on relevant parameters of the host response to bacteria or changes in the microbiome by processing biological samples from animal studies and human patients with CF. By providing diverse, yet complimentary tools and endpoints, the Host Response Core will greatly enhance the depth and accuracy of investigation. Finally, by providing support for preclinical studies and through interactions with the Clinical Core the HRC furthers translational research with the goal to better understand and correct the common sequela caused by mutations of CFTR through development of novel therapeutics for CF patients.